How to change modifier keys for navigation?
You can change default keyboard shortcuts in the User Preferences - ctrl+alt+u under Input tab:



Note that you can search for the keys currently used.

I would have to strongly recommend against that. Especially if you are a new user. Blender has an extremely complex hotkey system and you are likely to cause serious problems for yourself changing it. You are likely to break continuity and make some important functions inaccessible unless you are an experienced user familiar with all Blender's keyboard shortcuts and know exactly what you are doing.